Callis’s Voicepath PRI uses the latest cloud technology to deliver traditional voice services over a private connection.

Primary Rate Interface Integrated Services Digital Network (PRI ISDN)


With more efficient out-of-band signaling, Callis's PRI ISDN service utilizes 23 channels of a T-1's 24 channels for inbound and outbound calling. The 24th-or 'D' channel-is used for signaling information and call control. PRI service also allows you to:

• Receive caller ID telephone numbers on every call

• Transfer inbound calls to another location that is bridged in our network, instead of using voice channels on the PRI service to your location

Combine your local, long distance, and Internet services on a single access facility (should you choose to allocate bandwidth for this business-critical data need).